Microlensing Events by Proxima Centauri in 2014 and 2016
... F814W filters. Since the background stars are >8 mag fainter than Proxima, we obtained two sets of observations, a short one with an exposure time of 0.5 s (the minimum allowed exposure time with WFC3) in each filter, and a long one with an exposure time of 100 to 200 s. An extra set of short and lo ...
... F814W filters. Since the background stars are >8 mag fainter than Proxima, we obtained two sets of observations, a short one with an exposure time of 0.5 s (the minimum allowed exposure time with WFC3) in each filter, and a long one with an exposure time of 100 to 200 s. An extra set of short and lo ...
Herschel far-infrared observations of the Carina Nebula complex⋆
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
... Most stars in our Galaxy form in giant molecular clouds, as parts of rich stellar clusters or associations, containing highmass (M > 20 M ) stars. Recent investigations have shown that also our solar system formed close to massive stars, which had important influences on the early evolution of the ...
THE FUTURE IS NOW: THE FORMATION OF SINGLE LOW
... then decline monotonically for the four oldest bins. With this procedure they derived formation rates of 0.4, 4.5, and 0:9 ; 1013 pc3 yr1 for the 0.4, 0.6, and >0.8 M components, respectively. They also applied a binary correction to the He WD population. In the discussion that follows we will o ...
... then decline monotonically for the four oldest bins. With this procedure they derived formation rates of 0.4, 4.5, and 0:9 ; 1013 pc3 yr1 for the 0.4, 0.6, and >0.8 M components, respectively. They also applied a binary correction to the He WD population. In the discussion that follows we will o ...
Searching for Planets During Predicted Mesolensing Events: II
... well as MEarth, Kepler and other transit studies. If well designed, the monitoring programs will be guaranteed to either discover planets in orbits with semi-major axes smaller than about two Einstein radii, or else to rule out their presence. Planets on wider orbits may not all be discovered, but i ...
... well as MEarth, Kepler and other transit studies. If well designed, the monitoring programs will be guaranteed to either discover planets in orbits with semi-major axes smaller than about two Einstein radii, or else to rule out their presence. Planets on wider orbits may not all be discovered, but i ...
Chemical composition of cosmic dust in the solar vicinity
... - formed 2 kpc away from current position ...
... - formed 2 kpc away from current position ...
Betelgeuse – Challenging our Understanding for more than 2000
... to occur 1-‐2 years following the minimum in the 6-‐year RV curve. • Rapid photometric changes are not global • Observed events: large, rapid decrease in RV followed by 0.5 mag decrease in brightness ...
... to occur 1-‐2 years following the minimum in the 6-‐year RV curve. • Rapid photometric changes are not global • Observed events: large, rapid decrease in RV followed by 0.5 mag decrease in brightness ...
Astronomy Astrophysics IRAS 18357-0604 – an analogue of the galactic yellow hypergiant
... such as ρ Cas and HR8752 appear unable to support the Brackett series in emission (Yamamuro et al. 2007). Turning to the emission component of the spectrum and such cool temperatures are fully consistent with the presence of both Mg i and strong Ca ii emission which, given their ionisation potential ...
... such as ρ Cas and HR8752 appear unable to support the Brackett series in emission (Yamamuro et al. 2007). Turning to the emission component of the spectrum and such cool temperatures are fully consistent with the presence of both Mg i and strong Ca ii emission which, given their ionisation potential ...
Galaxy Classification Much of modern extragalactic astronomy deals
... spiral arms and bars have the Roman numeral I (like supergiant stars), and small, low-surface-brightness, irregular galaxies have the roman numeral V. Of course, since one doesn’t usually know a galaxy’s distance, it is somewhat difficult to estimate its true luminosity. The system therefore assumes ...
... spiral arms and bars have the Roman numeral I (like supergiant stars), and small, low-surface-brightness, irregular galaxies have the roman numeral V. Of course, since one doesn’t usually know a galaxy’s distance, it is somewhat difficult to estimate its true luminosity. The system therefore assumes ...
Towards a deterministic model of planetary formation. III. Mass
... dwarf stars) because the most successful radial velocity surveys have been conducted for these target stars which have cool and well defined atmospheric spectroscopic features. However, the search window is rapidly expanding to lower-mass stars as detection techniques are being refined in both radia ...
... dwarf stars) because the most successful radial velocity surveys have been conducted for these target stars which have cool and well defined atmospheric spectroscopic features. However, the search window is rapidly expanding to lower-mass stars as detection techniques are being refined in both radia ...
Large-eddy simulations of isolated disc galaxies with thermal and
... Nyx to run adaptively refined LES of an IDG as described in the following. To handle sub-resolution processes, such as star formac ???? RAS, MNRAS 000, 1–21 ...
... Nyx to run adaptively refined LES of an IDG as described in the following. To handle sub-resolution processes, such as star formac ???? RAS, MNRAS 000, 1–21 ...
Fundamental properties of core-collapse Supernova and GRB
... to estimate their synthetic photometry. We employ well-established observational criteria of spectroscopic classification and find that massive stars, depending on their initial mass and rotation, end their lives as red supergiants (RSG), yellow hypergiants (YHG), luminous blue variables (LBV), and ...
... to estimate their synthetic photometry. We employ well-established observational criteria of spectroscopic classification and find that massive stars, depending on their initial mass and rotation, end their lives as red supergiants (RSG), yellow hypergiants (YHG), luminous blue variables (LBV), and ...
YELLOW SUPERGIANTS IN THE ANDROMEDA GALAXY (M31)
... Maeder 2003, 2005) shown in Figure 3 and the corresponding lifetimes for the yellow supergiant stage given in Table 1.6 The metallicities shown span a range of 10, from sub-solar (z = 0.004, typical of the Small Magellanic Cloud (SMC)) to solar (z = 0.020) to super-solar (z = 0.040, typical of M31); ...
... Maeder 2003, 2005) shown in Figure 3 and the corresponding lifetimes for the yellow supergiant stage given in Table 1.6 The metallicities shown span a range of 10, from sub-solar (z = 0.004, typical of the Small Magellanic Cloud (SMC)) to solar (z = 0.020) to super-solar (z = 0.040, typical of M31); ...
part iv - the war medal 1939-45
... qualifying Naval personnel for the Atlantic Star, subject to the completion of two months service in an operational unit after earning the 1939-45 Star by six or two months operational service as the case may be. (b) Four months service as air crew in an operational unit, any two months of which qua ...
... qualifying Naval personnel for the Atlantic Star, subject to the completion of two months service in an operational unit after earning the 1939-45 Star by six or two months operational service as the case may be. (b) Four months service as air crew in an operational unit, any two months of which qua ...
Dark-matter halo mergers as a fertile environment for low
... paradigm as shown by Hirano et al. (2014). They suggested that in a slowly collapsing cloud, the compressional heating is reduced and may create the conditions for the HD cooling to become effective. In some of the above-mentioned papers (Bromm et al. 2002; Ripamonti 2007; McGreer & Bryan 2008), the ...
... paradigm as shown by Hirano et al. (2014). They suggested that in a slowly collapsing cloud, the compressional heating is reduced and may create the conditions for the HD cooling to become effective. In some of the above-mentioned papers (Bromm et al. 2002; Ripamonti 2007; McGreer & Bryan 2008), the ...
Massive quiescent galaxies at cosmic noon Robert Feldmann UC Berkeley
... mass has been monotonically decreasing since very early • ratedep redshifts. This of decrease is different for different halo masses. At moderate to high redshifts (z > 2), larger halo masses generically have larger average SFRs. However, at lower redshifts, the highest mass halos (Mh ! 1014 M! ) be ...
... mass has been monotonically decreasing since very early • ratedep redshifts. This of decrease is different for different halo masses. At moderate to high redshifts (z > 2), larger halo masses generically have larger average SFRs. However, at lower redshifts, the highest mass halos (Mh ! 1014 M! ) be ...
the article as PDF - Project VS
... The longer the time interval (in cycles) over which the data have been collected, the higher will be the resulting accuracy of the solution. If your period is slightly off, the discrepancy will accumulate as times goes on. In that case, the O-C diagram will look like an inclined straight line. If th ...
... The longer the time interval (in cycles) over which the data have been collected, the higher will be the resulting accuracy of the solution. If your period is slightly off, the discrepancy will accumulate as times goes on. In that case, the O-C diagram will look like an inclined straight line. If th ...
Luminous Blue Variables are Antisocial: Their Isolation Implies that
... stars and Wolf-Rayet (WR) stars. If the latter were true, then LBVs should be concentrated in young massive clusters like early O-type stars. This is decidedly not the case. Examining locations of LBVs in our Galaxy and the Magellanic Clouds reveals that, with only a few exceptions, LBVs systematica ...
... stars and Wolf-Rayet (WR) stars. If the latter were true, then LBVs should be concentrated in young massive clusters like early O-type stars. This is decidedly not the case. Examining locations of LBVs in our Galaxy and the Magellanic Clouds reveals that, with only a few exceptions, LBVs systematica ...
Population synthesis for double white dwarfs. I. Close - UvA-DARE
... First, they were mainly selected for study because of their supposed low mass, since this is a clear indication of binarity (Saffer et al. 1988; Marsh et al. 1995). Secondly, for the mass determinations and the measurement of the radial velocities the white dwarfs must be sufficiently bright. A thir ...
... First, they were mainly selected for study because of their supposed low mass, since this is a clear indication of binarity (Saffer et al. 1988; Marsh et al. 1995). Secondly, for the mass determinations and the measurement of the radial velocities the white dwarfs must be sufficiently bright. A thir ...
Envelope inflation in massive stars near the Eddington limit
... Evolution of single stars Stars are self-gravitating balls of hot plasma that are burning hydrogen in their cores for most (∼ 90%) of their lifetime, also called the main-sequence phase. The time required by a star to burn its nuclear fuel at a given luminosity is called the nuclear timescale. The n ...
... Evolution of single stars Stars are self-gravitating balls of hot plasma that are burning hydrogen in their cores for most (∼ 90%) of their lifetime, also called the main-sequence phase. The time required by a star to burn its nuclear fuel at a given luminosity is called the nuclear timescale. The n ...
A FUSE Survey of Coronal Forbidden Lines in Late
... We searched for evidence of coronal forbidden lines in the 900–1200 Å region in our sample of stellar spectra. Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with lo ...
... We searched for evidence of coronal forbidden lines in the 900–1200 Å region in our sample of stellar spectra. Because of our relatively poor knowledge of the rest wavelengths of these lines, the relatively weak signal of the coronal lines, and the moderate likelihood of coincidental blends with lo ...
Extragalactic Globular Cluster Systems
... The globular clusters that were once within the merging protogalaxies are so dense that they survive intact and will orbit freely within the Galaxy. The surviving protogalaxies may be the precursors of the old satellite galaxies, some of which host old globular clusters such as Fornax, whose morphol ...
... The globular clusters that were once within the merging protogalaxies are so dense that they survive intact and will orbit freely within the Galaxy. The surviving protogalaxies may be the precursors of the old satellite galaxies, some of which host old globular clusters such as Fornax, whose morphol ...
UNIT 4 - Galaxies XIV. The Milky Way A. Structure
... Galaxy)- all gravitationally bound together Local Group's diameter is approximately 6.5 million light years across ...
... Galaxy)- all gravitationally bound together Local Group's diameter is approximately 6.5 million light years across ...
how dry is the brown dwarf desert? quantifying the
... stellar systems are not present in any of the Doppler target lists. The triangles in Figure 1 indicate that the ones left out are spread more or less evenly in B V space spanned by the gray parallelogram. Similarly in Figure 2, 1295 (= 3296–2001), or 39%, are not included in any Doppler target lis ...
... stellar systems are not present in any of the Doppler target lists. The triangles in Figure 1 indicate that the ones left out are spread more or less evenly in B V space spanned by the gray parallelogram. Similarly in Figure 2, 1295 (= 3296–2001), or 39%, are not included in any Doppler target lis ...
SN 2006gy: DISCOVERY OF THE MOST LUMINOUS
... O-type stars and WR stars have shown that their winds are highly clumped, requiring that their mass-loss rates through line-driven winds on the main sequence could be an order of magnitude lower than previously believed (Fullerton et al. 2006; Bouret et al. 2005). In that case, for stars with initia ...
... O-type stars and WR stars have shown that their winds are highly clumped, requiring that their mass-loss rates through line-driven winds on the main sequence could be an order of magnitude lower than previously believed (Fullerton et al. 2006; Bouret et al. 2005). In that case, for stars with initia ...
Main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hertzsprung and Henry Norris Russell. Stars on this band are known as main-sequence stars or ""dwarf"" stars.After a star has formed, it generates thermal energy in the dense core region through the nuclear fusion of hydrogen atoms into helium. During this stage of the star's lifetime, it is located along the main sequence at a position determined primarily by its mass, but also based upon its chemical composition and other factors. All main-sequence stars are in hydrostatic equilibrium, where outward thermal pressure from the hot core is balanced by the inward pressure of gravitational collapse from the overlying layers. The strong dependence of the rate of energy generation in the core on the temperature and pressure helps to sustain this balance. Energy generated at the core makes its way to the surface and is radiated away at the photosphere. The energy is carried by either radiation or convection, with the latter occurring in regions with steeper temperature gradients, higher opacity or both.The main sequence is sometimes divided into upper and lower parts, based on the dominant process that a star uses to generate energy. Stars below about 1.5 times the mass of the Sun (or 1.5 solar masses (M☉)) primarily fuse hydrogen atoms together in a series of stages to form helium, a sequence called the proton–proton chain. Above this mass, in the upper main sequence, the nuclear fusion process mainly uses atoms of carbon, nitrogen and oxygen as intermediaries in the CNO cycle that produces helium from hydrogen atoms. Main-sequence stars with more than two solar masses undergo convection in their core regions, which acts to stir up the newly created helium and maintain the proportion of fuel needed for fusion to occur. Below this mass, stars have cores that are entirely radiative with convective zones near the surface. With decreasing stellar mass, the proportion of the star forming a convective envelope steadily increases, whereas main-sequence stars below 0.4 M☉ undergo convection throughout their mass. When core convection does not occur, a helium-rich core develops surrounded by an outer layer of hydrogen.In general, the more massive a star is, the shorter its lifespan on the main sequence. After the hydrogen fuel at the core has been consumed, the star evolves away from the main sequence on the HR diagram. The behavior of a star now depends on its mass, with stars below 0.23 M☉ becoming white dwarfs directly, whereas stars with up to ten solar masses pass through a red giant stage. More massive stars can explode as a supernova, or collapse directly into a black hole.